Question: Battery Power

Thank You John,
I have the veh wired as per redarc diagram and have purchased a 250s duel ctek yet to be wired in to van battery. Was suggested by the agent that the 250 goes onto van battery and I run a seperate new 4b&s direct to 3 way fridge which would then be isolated from van battery and only run from cranking battery,hence the van battery would always be fully maintained. Sounds complicated,would that be the way to go? Previously the van batt would always be low even if travelling all day running 3way fridge.
regards cherry.

What you suggest is the current thinking. Obviously you need to isolate the fridge from the cranking battery when the engine is not running. You could do this by connecting to the Redarc, using a motion sensitive 'fridge switch' or a relay operated by the ignition switch.

Hi Cherry,

First, a belated welcome aboard!

Your proposal sounds good. As Rod points out though it is essential that the line running to the 3 way fridge and dc-dc charger be disconnected when the engine isn't running. otherwise the fridge (and the dc-dc charger) will be run by the vehicle's aux battery. I use a relay for this, but as Rod suggests, a trembler fridge switch would do it too.

Note that both negative and positive wires should be run from engine bay to van and anderson plugs be used between vehicle and van. If the fridge and ctek 250s dual are to run from the same cable, yes, 4 b&s sounds good.


Cheers

John

"4 b&s sounds good"
4B&S is way over the top. 6B&S is more than adequate.

"I run a seperate new 4b&s direct to 3 way fridge"
8B&S on the vehicle is sufficient and if under 4M on the caravan 6mm auto cable 4.57mm2 would be sufficient. As long as you have 12.5V at the fridge element is all that is needed.

Paul,

If I was wiring this rig, I'd have two separate circuits using 6 B&S, one for the fridge, one for the battery/charger. Yes 4 B&S is pretty big, but this installation has been seen by someone who knows their stuff and has decided on a single circuit using 4 B&S. If you or I saw it we might decide the same.

Either 4B&S or two runs of 6B&S will be required to deliver anything like 12.5 volts at the fridge when its drawing 12-15A and the charger another 20-25A through a total length (including return) of probably 10-15 metres.

John

run 6 BS to Anderson plug on rear of vehicle for Ctek D250S. On the van Anderson plug to Ctek D250S 8 BS is the go. Keep the D250S within 1M of the battery.

run 8 BS to Anderson plug on vehicle through a Victron Cyrix Battery Isolator for your fridge. Agree 6mm auto cable on van for fridge is adequate. Victron Cyrix battery isolator superior and cheaper than Redarc. Redarc $100 Victron Cyrix $60

should have stated these MUST come off your main vehicle start battery and not your auxiliary battery. The Cyrix and Ctek will drop out automatically at 12.8V